import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Scanner;

/**
 * 
 */

/**
 * @author zhongfang
 *
 */
public class Expectation {

	public static double getResult(int p,int q,int n) {
		double result=0;
		HashMap<Integer, Double> oldP=new HashMap<>();
		oldP.put(0, 1.0);//初始化为次数0，概率1
		for(int i=0;i<n;i++){
			oldP=getNextPrize(oldP, p, q);
			p/=2;
		}
		//最后一次获奖所有长度及概率
		for (Entry<Integer, Double> entry : oldP.entrySet()) {
			int lastLength=entry.getKey();
			double lastP=entry.getValue();
			result+=(lastLength*lastP);
		}
		return result;
	}
	//第i-1次获奖到i次获奖，计算概率和对应长度
	public static HashMap<Integer, Double> getNextPrize(HashMap<Integer, Double> oldProba,int p,int q) {
		HashMap<Integer, Double> result=new HashMap<>();
		ArrayList<Integer> lengthArr;//获得奖的长度和对应的概率
		ArrayList<Double> pArrayList;
		ArrayList<Double> allP=new ArrayList<>();//当前获得奖的概率即p+q+q+q+...
		int i=0;
		while (p+q*i<100) {
			double d=((double)p+q*i)/100;
			allP.add(d);
			i++;
		}
		allP.add(1.0);//最后一次概率>=100,一定能得奖
		
		int totalLength=allP.size();
		lengthArr=new ArrayList<>(totalLength);
		pArrayList=new ArrayList<>(totalLength);
		lengthArr.add(1);
		pArrayList.add((double)p/100);
		i=1;
		while (i<totalLength) {
			double d=pArrayList.get(i-1);//上一步获奖了
			double last=allP.get(i-1);
			if(last!=0){
				d/=last;
				d*=(1-last);
				d*=allP.get(i);//这一步获奖的概率
			}else {//如果上一次概率是0，则直接不考虑，(是0的只可能是p，则d可以直接赋值为q）
				d=(double)q/100;
			}
			
			lengthArr.add(i+1);
			pArrayList.add(d);//从上一次获奖到当前这一步能获得奖的概率
			i++;
		}
		for (Entry<Integer, Double> entry : oldProba.entrySet()) {
			int lastLength=entry.getKey();
			double lastP=entry.getValue();
			Iterator<Integer> itr1=lengthArr.iterator();
			Iterator<Double> itr2=pArrayList.iterator();
			while (itr2.hasNext()) {
				Double plusP = (Double) itr2.next();
				int plusLength=(int)itr1.next();
				double currentP=lastP*plusP;
				int currentLength=lastLength+plusLength;
				if(currentP==0){
					continue;
				}
				if(result.containsKey(currentLength)){//如果已经有了这样的长度，则可以直接加概率
					currentP+=result.get(currentLength);
				}
				result.put(currentLength, currentP);
			}
		}
		return result;
	}
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner=new Scanner(System.in);
		int P=scanner.nextInt();
		int Q=scanner.nextInt();
		int N=scanner.nextInt();
		System.out.println(String.format("%.2f",getResult(P, Q, N)));
	}

}
